Conventionally, for such type of equipment is provided, for example, a load storing equipment in a clean room is provided in Japanese Laid-open Patent No. 3-152004. In such conventional structure, a load storage part is provided with both front and back faces being open, filters placed in the back face side of the load storage part, and an air supply path formed in the back of the filters through partition walls. Then, a fan having an air outlet in communication with the air supply path is placed beneath the load storage part, so that clean air passing through the load storage part is drawn by the fan through a suction part. A shell of the main body is employed backside the partition walls so that an air collecting path is formed between the partition walls and the shell, and comes in communication with a section chamber in which the fan is placed.
According to such conventional structure, a flow of air discharged from the air outlet of the fan is directed upward in the air supply path, cleaned to a high cleanliness while passing through the filters, and supplied from the back face side to the load storage part. Therefore, within the load storage part, the high cleanliness is maintained by the clean air flowing from the back face to the front face. The clean air flowing across the load storage part is succeedingly aspired by the fan, and recirculated for repetitive use.
In such operation, because a suction force of the fan also effects to the air collecting path, and induces a negative pressure in the air collecting path, a dirty air leaking to the air collecting path from a joint of the partition walls is, therefore, immediately drawn into the fan by means of the suction force, and never flows outside.
According to the conventional structure, however, as the air supply path is at a high positive pressure, a dirty air that has not passed through the filter may leak from the joint between a back frame forming the load storage part and the filter, and flow into the load storage part. Therefore, application of such laborsome and expensive sealing as coking has been required to the joint. In addition, the structure has been complicated, because of the air collecting path formed through the partition wall in the backside of the air supply path. Moreover, the entire system has been cumbresome, and the lowermost shelf of the load storage part has been at a high level, causing an inefficient use of space, as a section chamber for the fan is formed beneath the load storage part. Although such arrangement that the fan is placed above the load storage part may be considered, the entire system comes to be cumbersome similarly as the case already mentioned, where the filter is placed beneath the storage part.